Powder sintering methods are classified into one with no pressurization and one with pressurization such as hot pressing and hot isostatic pressing. While the sintering method with no pressurization enables reduction of oxygen in a sintered body by virtue of performing sintering in a reducing atmosphere such as hydrogen or the like, it is thought in the powder sintering method with pressurization such as hot isostatic pressing or the like that it is difficult to remarkably reduce oxygen after sealing because powder is confined in a capsule such as metallic container or the like to be subjected to sintering, and so the method depends much upon reduction of oxygen quantity in a material powder.
Recently, proposed as a method of oxygen reduction in a sintered body is, for example, a method of moving and reducing oxygen from a material being sintered, by having a getter metal, from which an oxide is formed at a sintering temperature to be lower in oxygen dissociation pressure than an oxide formed from a metallic material being sintered, existing in an inner portion of a metallic capsule in contact with the material being sintered, when hot isostatic pressing is carried out (for example, JP-A-2000-144396).
JP-A-2000-144396 discloses removal of oxygen from a material being sintered, by having a getter material existing in an inner portion of a metallic container in contact with the material being sintered, to permit oxygen existing in the material being sintered to diffuse on a surface of the material being sintered, to combine with the getter material.
In the case where a getter material together with a material being sintered is sealed in a metallic container in a manner to be made existent in a portion of the metallic container in contact with the material being sintered, and pressurized sintering is performed, however, effectiveness of oxygen removal caused by the getter material is liable to appear in only that surface layer portion of a sintered body, which comes into contact with the getter material, and oxygen in the sintered body cannot be adequately reduced, so that there remains a problem that it is not possible to generally evenly reduce oxygen remained in the sintered body.